STUDY ON THE ADSORPTION OF HEXAVALENT CHROMIUM BY NANO-ALUMINA PARTICLES

The alumina nanoparticles were synthesized by chemical precipitation process and characterized by BET, XRD and TEM. Results showed that the alumina nanoparticles were γ-alumina phase, the diameter of the particles and the specific surface area of alumina nanoparticles were between 7～10 nm and 117.986 m2/g, respectively. The adsorption characteristics of alumina nanoparticles were investigated. The results indicated that the removal efficiency of Cr（Ⅵ）can reach 96.1% when the initial pH value was 2, the dosage of alumina nanoparticles was 2g/L and Cr（Ⅵ）concentration was 15 mg/L within 4 hours. Results of kinetics showed that the adsorption of Cr（Ⅵ）by alumina nanoparticles could well described by the pseudo second order kinetic model (R2≥0.945). Isotherm adsorption capacity of alumina nanoparticles can fit well to Freundlich equation. Additionally, the value of the correlation (R2) for the isotherm model was close to 1. It was found that the adsorption was the process of spontaneity and exotherm, and it was more effective for the removal of hexavalent chromium from aqueous solution at lower temperatures.